<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>登录</title>
</head>
<body>
<center>
<form action="login_SF.php" method="post">
    <h3>登录</h3>
    <p><input type="text" placeholder="手机/邮箱/个人空间地址" name="username" id="input1" onblur="judge1()"
              style="height: 25px;width: 250px"></p>
    <p><input type="password" placeholder="请输入密码" name="paw" id="input2" onblur="judge2()"
              style="height: 25px;width: 250px"></p>
    <p><input type="submit" value="登录" onclick="judge()"
              style="height: 25px;width: 250px;background-color: #fe7520;color: white;"></p>
</form>
</center>>
</body>
<script type="text/javascript">
    function judge1() {
        var input1 = document.getElementById('input1');
        if (input1.value == '') {
            alert('账号不能为空！');
            return;
        }
    }

    function judge2() {
        var input2 = document.getElementById('input2');
        if (input2.value == '') {
            alert('密码不能为空！');
            return;
        }
    }
</script>
</html>